1. Field of the Invention
This invention relates to a magnetic tape cassette provided with a guard panel. This invention particularly relates to an improvement in the inner cover guide configuration of a magnetic tape cassette provided with a guard panel of a dual configuration.
2. Description of the Prior Art
In general, magnetic video tape cassettes are provided with a guard panel for covering a magnetic tape exposed at the front face of the cassette body. Particularly, as the guard panel in a magnetic tape cassette for a small video tape recorders, such as an 8 mm video tape recorder, there has heretofore been known a guard panel comprising an outer cover for covering the outer surface of the magnetic tape, and an inner cover supported on the outer cover for movement in synchronization with opening/closing of the outer cover and covering the inner surface of the magnetic tape when the outer cover is closed.
When the guard panel is combined with the upper and lower halves of the cassette case during the assembling process of the magnetic tape cassette provided with the aforesaid guard panel, the guard panel is first mounted on the upper half which has been superposed on the lower half, and then the lower half is combined with the guard panel. However, after the guard panel is mounted on the upper half, the guard panel readily disengages from the upper half, and it is not always possible to combine the lower half with the guard panel.
Specifically, the upper half is provided with engagement holes for supporting the outer cover of the guard panel, and the lower half is provided with guide grooves for guiding the inner cover. When the guard panel is opened or closed, the inner cover is opened or closed with respect to the outer cover. Therefore, when the lower half is combined with the guard panel, supporting of the outer cover by the upper half is maintained, and at the same time the inner cover (i.e. guide bosses thereof) must be fitted to the guide grooves of the lower half. At this time, the outer cover readily disengages from the upper half. This is presumably because the engagement holes of the upper half for supporting shafts of the outer cover are semicircular and form complete circular holes when combined with semicircular holes of the lower half. Therefore, the rejection rate increases when the upper and lower halves are subjected to vibration during the assembling process or the assembling speed is increased. Thus a very real problem arises in the assembling process.